In a conventional quad-flat no-leads (QFN) package, bumps or copper pillars separate a chip containing an inductive element from a package body containing a metal package ground. These pillars or bumps are short and result in little separation between the chip and the metal package ground. The inductive element generates a magnetic field that induces or causes eddy currents in the metal package ground. The magnitude of the induced eddy currents is dependent, in part, on the distance separating the source of the magnetic field (the inductive element) and the metal package ground. The induced eddy currents are problematic because they have a parasitic effect and degrade the performance of the inductive element. By adding a hollow space in the package under the inductive element and between the inductive element and the metal package ground, the performance of the inductive element can be improved due to the increased separation of the inductive element and metal package ground. However, this design degrades the heat dispassion capabilities of the package. Accordingly, there is a need for integrated circuit package structures and methods that improve upon conventional methods by reducing the induced eddy currents while providing improved heat dissipation.
The inventive features that are characteristic of the teachings, together with further features and advantages, are better understood from the detailed description and the accompanying figures.